The invention relates to a method for making a pump ring for a two-stage vacuum pump with a one-piece rotor system of three sections whose end sections form the two pump stages and whose middle section forms an intermediate bearing, the diameters of the bearing section and of the rotor section forming the first vacuum stage being equal.
It is known from DE-OS 23 54 039 that the designer of vacuum pumps endeavors to minimize the number of parts from which a vacuum pump is made. The two-stage vacuum pump disclosed in this patent application, however, still requires two (radially divided) pump rings, which have to be made separately. The danger of cumulative tolerances impairing pump action is thus created.
It is the object of the present invention to propose a method for the production of a pump ring of the kind described above in which the tolerances involved in the pump are appreciably reduced while achieving lower manufacturing cost.